Selective heteroaryloxy-acetamide-based herbicides

ABSTRACT

The invention relates to novel herbicidal synergistic active compound combinations comprising heteroaryloxy-acetamides and known herbicidally active compounds and/or safeners listed in the description, which active compound combinations can be used with particularly good results for the selective control of weeds in crops of various useful plants.

This application is a division of U.S. application Ser. No. 10/296,006,filed Nov. 20, 2002, which was filed under 35 U.S.C. 371 as a nationalstage application of International Application No. PCT/EP01/05242, filedMay 9, 2001, which was published in German as International PatentPublication WO 01/89301 on Nov. 29, 2001, which is entitled to the rightof priority of German Patent Application Nos. 100 25 306.7, filed May22, 2000, and 100 41 619.5, filed Aug. 24, 2000.

The invention relates to novel selective-herbicidal synergistic activecompound combinations comprising known heteroaryloxy-acetamides andknown herbicidally active compounds and/or compounds which improve cropplant tolerance, which active compound combinations can be used withparticularly good results for the selective control of weeds in crops ofvarious useful plants.

As strong herbicides, which are active in particular againstmonocotyledonous weeds, heteroaryloxy-acetamides have been the subjectof a number of patent applications (cf. EP-A 5501, EP-A 18497, EP-A29171, EP-A 94514, EP-A 100044, EP-A 100045, EP-A 161602, EP-A 195237,EP-A 348734, EP-A 348737, DE-A 4317323). However, the activity of thesecompounds and/or their compatibility with crop plants is/are not alwaysentirely satisfactory.

Furthermore, active compound combinations of heteroaryloxy-acetamidesand other herbicidally active compounds for obtaining a synergisticeffect (cf. WO-A 94/02014, WO-A-96/07323, WO-A-96/11575, WO-A-96/17519,WO-A-98/08383, cf. also U.S. Pat. No. 5,858,920, U.S. Pat. No.5,945,379, U.S. Pat. No. 5,985,797) or of heteroaryloxy-acetamides andcompounds which can improve the crop plant tolerance of herbicides (cf.DE-A 3418167, cf. also U.S. Pat. No. 5,858,920) have been disclosed.However, the use properties of these combination products are likewisenot always entirely satisfactory.

Surprisingly, it has now been found that a number of known activecompounds from the group of the heteroaryloxy-acetamides, when usedtogether with known herbicidally active compounds from various substanceclasses and/or compounds which improve crop plant tolerance, showpronounced synergistic effects with respect to the action against weedsand/or have significantly improved crop plant tolerance and can be usedparticularly advantageously as broad-spectrum combination preparationsfor the selective control of weeds in crops of useful plants, such as,for example, in cotton, barley, maize, potatoes, oilseed rape, rice,soya beans, sunflowers, wheat and sugar cane.

The invention provides selective herbicidal compositions, characterizedin that they comprise an effective amount of an active compoundcombination consisting of

-   -   (a) a heteroaryloxy-acetamide of the general formula (I)        -   in which        -   Ar represents optionally halogen-, C₁-C₄-alkyl- or            C₁-C₄-halogenoalkyl-substituted phenyl,        -   Het represents thiadiazolyl, which is substituted by halogen            or by in each case optionally halogen-substituted            C₁-C₄-alkyl or phenyl, and        -   R represents alkyl, alkenyl or alkinyl having in each case            up to 4 carbon atoms,        -   (“active compounds of group 1”) and    -   (b) one or more compounds from a second group of herbicides        containing the active compounds mentioned hereinbelow:

-   1H-1,2,4-triazol-3-amine (amitrole),    2-[2,4-dichloro-5-(2-propinyloxy)-phenyl]-5,6,7,8-tetrahydro-1,2,4-triazolo-[4,3-a]-pyridin-3    (2H)-one (azafenidin),    N-(4,6-dimethoxy-pyrimidin-2-yl)-N′-[1-methyl-4-(2-methyl-2H-tetrazol-5-yl)-1H-pyrazol-5-ylsulphonyl]urea    (azimsulfuron),    N-benzyl-2-(4-fluoro-3-trifluoromethyl-phenoxy)-butanamide    (beflubutamid),    N-butyl-N-ethyl-2,6-dinitro-4-trifluoromethyl-benzeneamine    (benfluralin), methyl    2-[2-[4-(3,6-dihydro-3-methyl-2,6-dioxo-4-trifluoromethyl-1(2H)-pyrimidinyl-phenoxymethyl]-5-ethyl-phenoxy-propanoate    (benzfendizone),    3-(2-chloro-4-methylsulphonyl-benzoyl)-4-phenylthio-bicyclo-[3.2.1]-oct-3-en-2-one    (benzobicyclon), [1,1-dimethyl-2-oxo-2-(2-propenyloxy)]-ethyl    2-chloro-5-(3,6-dihydro-3-methyl-2,6-dioxo-4-trifluoromethyl-1(2H)-pyrimidinyl)-benzoate    (butafenacil-allyl),    2-(1-ethoximino-propyl)-3-hydroxy-5-[2,4,6-trimethyl-3-(1-oxo-butyl)-phenyl]-2-cyclohexen-1-one    (butroxydim),    2-[1-[(3-chloro-2-propenyl)-oxy-imino]-propyl]-3-hydroxy-5-(tetrahydro-2H-pyran-4-yl)-2-cyclohexen-1-one    (caloxydim, tepraloxydim), ethyl    2-chloro-3-[2-chloro-5-(1,3,4,5,6,7-hexahydro-1,3-dioxo-2H-isoindol-2-yl)-phenyl]-2-propanoate    (cinidon-ethyl),    2-[1-[2-(4-chloro-phenoxy)]-propoxyamino-butyl]-5-(tetrahydro-2H-thiopyran-3-yl)-1,3-cyclohexanedione    (clefoxydim),    (E,E)-(+)-2-[1-[[(3-chloro-2-propenyl)-oxy]-imino]-propyl]-3-hydroxy-2-cyclohexen-1-one    (clethodim), methyl    3-chloro-2-[[(5-ethoxy-7-fluoro[1,2,4]triazolo[1,5-c]pyrimidin-2-yl)sulphonyl]amino]-benzoate    (cloransulam-methyl),    2-(1-ethoximinobutyl)-3-hydroxy-5-(tetrahydro-2H-thiopyran-3-yl)-2-cyclohexen-1-one    (cycloxydim),    N-(2,6-dichloro-phenyl)-5-ethoxy-7-fluoro-[1,2,4]-triazolo-[1,5-c]-pyrimidine-2-sulphonamide    (diclosulam),    2-[1-[(3,5-difluoro-phenyl)-amino-carbonyl-hydrazono]-ethyl]-pyridine-3-carboxylic    acid (diflufenzopyr),    (S)-2-chloro-N-(2,4-dimethyl-3-thienyl)-N-(2-methoxy-1-methyl-ethyl)-acetamide    (dimethenamid-P),    2-[2-(3-chloro-phenyl)-oxiranylmethyl]-2-ethyl-1H-indene-1,3(2H)-dione    (epropodan), (R)-ethyl    2-[4-(6-chloro-benzoxazol-2-yl-oxy)-phenoxy]-propanoate    (fenoxaprop-P-ethyl),    N-(2,6-difluoro-phenyl)-8-fluoro-5-methoxy-[1,2,4]-triazolo-[1,5-c]-pyrimidine-2-sulphonamide    (florasulam), butyl    (R)-2-[4-(5-trifluoromethyl-pyridin-2-yl-oxy)-phenoxy]-propanoate    (fluazifop-P-butyl), the sodium salt of    4,5-dihydro-3-methoxy-4-methyl-5-oxo-N-[(2-trifluoromethoxy-phenyl)-sulphonyl]-1H-1,2,4-triazole-1-carboxamide    (flucarbazone-sodium),    ethyl[2-chloro-4-fluoro-5-(5-methyl-6-oxo-4-trifluoromethyl-1    (6H)-pyridazinyl)-phenoxy]-acetate (flufenpyr),    2-[7-fluoro-3,4-dihydro-3-oxo-4-(2-propinyl)-2H-1,4-benzoxazin-6-yl]-4,5,6,7-tetrahydro-1H-isoindole-1,3-dione    (flumioxazin), the sodium salt of    N-(4,6-dimethoxy-pyrimidin-2-yl)-N′-(3-methoxycarbonyl-6-trifluoromethyl-pyridin-2-yl-sulphonyl)-urea    (flupyrsulfuron-methyl-sodium),    2-[[[[(4,6-dimethoxy-2-pyrimidinyl)-amino]-carbonyl]-amino]-sulphonyl]-4-formylamino-N,N-dimethyl-benzamide    (foramsulfuron),    (R)-2-[4-(3-chloro-5-trifluoromethyl-pyridin-2-yl-oxy)-phenoxy]-propanoic    acid (and its methyl, -2-ethoxy-ethyl and butyl esters) (haloxyfop,    -methyl, -P-methyl, -ethoxyethyl, -butyl),    2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl)-5-(methoxymethyl)-3-pyridinecarboxylic    acid (imazamox), the sodium salt of    N-(4-methoxy-6-methyl-1,3,5-triazin-2-yl)-N′-(5-iodo-2-methoxycarbonyl-phenylsulphonyl)-urea    (iodosulfuron-methyl-sodium),    (4-chloro-2-methylsulphonyl-phenyl)-(5-cyclopropyl-isoxazol-4-yl)-methanone    (isoxachlortole), methyl    2-[[[[(4,6-dimethoxy-2-pyrimidinyl)-amino]-carbonyl]-amino]-sulphonyl]-4-[[(methylsulphonyl)-amino]-methyl]-benzoate    (mesosulfuron),    2-(4-methylsulphonyl-2-nitro-benzoyl)-1,3-cyclohexanedione    (mesotrione),    3-[1-(3,5-dichloro-phenyl)-1-i-propyl]-2,3-dihydro-6-methyl-5-phenyl-4H-1,3-oxazin-4-one    (oxaziclomefone),    2-chloro-1-(3-ethoxy-4-nitro-phenoxy)-4-trifluoromethyl-benzene    (oxyfluorfen),    2-(2,2-difluoro-ethoxy)-N-(5,8-dimethoxy[1,2,4]triazolo[1,5-c]pyrimidin-2-yl)-6-trifluoromethylbenzenesulphonamide    (penoxsulam),    2-chloro-N-(2-ethoxy-ethyl)-N-(2-methyl-1-phenyl-1-propenyl)-acetamide    (pethoxamid), the sodium salt of methyl    2-[[[(4,5-dihydro-4-methyl-5-oxo-3-propoxy-1H-1,2,4-triazol-1-yl)-carbonyl]-amino]-sulphonyl]-benzoate    (procarbazone-sodium),    1-chloro-N-[2-chloro-4-fluoro-5-[(6S,7aR)-6-fluoro-tetrahydro-1,3-dioxo-1H-pyrrolo[1,2-c]imidazol-2(3H)-yl]-phenyl]-methanesulphonamide    (profluazol),    (R)-[2-[[(1-methyl-ethylidene)-amino]-oxy]-ethyl]2-[4-(6-chloro-2-quinoxalinyloxy)-phenoxy]-propanoate    (propaquizafop),    2-chloro-N-(2-ethyl-6-methyl-phenyl)-N-[(1-methyl-ethoxy)-methyl]-acetamide    (propisochlor),    1-(3-chloro-4,5,6,7-tetrahydropyrazolo[1,5-a]pyridin-2-yl)-5-(methyl-2-propinylamino)-1H-pyrazol-4-carbonitrile    (pyraclonil), ethyl    [2-chloro-5-(4-chloro-5-difluoromethoxy-1-methyl-1H-pyrazol-3-yl)-4-fluoro-phenoxy]-acetate    (pyraflufen-ethyl), 6-chloro-3-phenyl-pyridazin-4-ol (pyridatol),    7-[(4,6-dimethoxy-2-pyrimidinyl)-thio]-3-methyl-1(3H)-isobenzofuranone    (pyriftalide), methyl 2-(4,6-dimethoxy-pyrimidin-2-yl-oxy)-benzoate    (pyriminobac-methyl), the sodium salt of    2-chloro-6-(4,6-dimethoxy-pyrimidin-2-ylthio)-benzoate    (pyrithiobac-sodium), 3,7-dichloro-quinoline-8-carboxylic acid    (quinchlorac),    (R)-2-[4-(6-chloro-2-quinoxalinyloxy)-phenoxy]-propanoic acid (and    its ethyl and tetrahydro-2-furanyl-methyl esters)    (quizalofop-P-ethyl, -P-tefuryl), methyl    2-difluoromethyl-5-(4,5-dihydro-thiazol-2-yl)-4-(2-methyl-propyl)-6-trifluoromethyl-pyridine-3-carboxylate    (thiazopyr), (3,5,6-trichloro)-pyridin-2-yl-oxy-acetic acid    (triclopyr), the sodium salt of    N-[[(4,6-dimethoxy-2-pyrimidinyl)-amino]-carbonyl]-3-(2,2,2-trifluoro-ethoxy)-2-pyridinesulphonamide    (trifloxysulfuron),    N-[4-dimethylamino-6-(2,2,2-trifluoro-ethoxy)-1,3,5-triazin-2-yl]-N′-(2-methoxycarbonyl-phenylsulphonyl)-urea    (triflusulfuron-methyl),    N-[[(4,6-dimethoxy-2-pyrimidinyl)-amino]-carbonyl]-3-(N-methyl-N-methylsulphonyl-amino])-2-pyridinesulphonamide    (cf. WO-A-92/10660),    -   (“active compounds of group 2”),    -   and, if appropriate, additionally    -   (c) a compound which improves crop plant tolerance, from amongst        the following group of compounds:

-   4-dichloroacetyl-1-oxa-4-aza-spiro[4.5]-decane (AD-67),    1-dichloroacetyl-hexahydro-3,3,8a-trimethylpyrrolo[1,2-a]-pyrimidin-6(2H)-one    (dicyclonon, BAS-145138),    4-dichloroacetyl-3,4-dihydro-3-methyl-2H-1,4-benzoxazine    (benoxacor), 1-methyl-hexyl 5-chloro-quinoline-8-oxy-acetate    (cloquintocet-mexyl), α-(cyanomethoximino)-phenylacetonitrile    (cyometrinil),    2,2-dichloro-N-(2-oxo-2-(2-propenylamino)-ethyl)-N-(2-propenyl)-acetamide    (DKA-24), 2,2-dichloro-N,N-di-2-propenyl-acetamide (dichlormid),    N-(4-methyl-phenyl)-N′-(1-methyl-1-phenyl-ethyl)-urea (dymron),    4,6-dichloro-2-phenyl-pyrimidine (fenclorim), ethyl    1-(2,4-dichloro-phenyl)-5-trichloromethyl-1H-1,2,4-triazole-3-carboxylate    (fenchlorazol-ethyl), phenylmethyl    2-chloro-4-trifluoromethyl-thiazole-5-carboxylate (flurazole),    4-chloro-N-(1,3-dioxolan-2-yl-methoxy)-α-trifluoro-acetophenone    oxime (fluxofenim),    3-dichloroacetyl-5-(2-furanyl)-2,2-dimethyl-oxazolidine (furilazole,    MON-13900), ethyl 4,5-dihydro-5,5-diphenyl-3-isoxazolecarboxylate    (isoxadifen-ethyl),    diethyl-1-(2,4-dichlorophenyl)-4,5-dihydro-5-methyl-1H-pyrazole-3,5-dicarboxylate    (mefenpyr-diethyl), 2-dichloromethyl-2-methyl-1,3-dioxolane    (MG-191), 1,8-naphthalenedicarboxylic anhydride,    α-(1,3-dioxolan-2-yl-methoximino)-phenylacetonitrile (oxabetrinil),    2,2-dichloro-N-(1,3-dioxolan-2-yl-methyl)-N-(2-propenyl)-acetamide    (PPG-1292), 3-dichloroacetyl-2,2-dimethyl-oxazolidine (R-28725),    3-dichloroacetyl-2,2,5-trimethyl-oxazolidine (R-29148), methyl    1-(2-chloro-phenyl)-5-phenyl-1H-pyrazole-3-carboxylate and    N-(2-methoxy-benzoyl)-4-[(methylamino-carbonyl)-amino]-benzenesulphonamide    -   (“active compounds of group 3”).

Preferred meanings of the radicals listed in the formula (I) shown aboveare illustrated below.

Ar preferably represents optionally fluorine-, chlorine-, bromine-,methyl-, ethyl- or trifluoromethyl-substituted phenyl.

Het preferably represents 1,2,4-thiadiazolyl or 1,3,4-thiadiazolyl whichis substituted by fluorine, chlorine, bromine or by in each caseoptionally fluorine- and/or chlorine-substituted methyl, ethyl, n- ori-propyl or phenyl.

R preferably represents methyl, ethyl, n- or i-propyl, n-, i-, s- ort-butyl, 2-propenyl, 1-methyl-2-propenyl, 2-butenyl, 2-propinyl,1-methyl-2-propinyl, 2-butinyl.

Ar particularly preferably represents optionally fluorine-, chlorine-,bromine-, methyl- or trifluoromethyl-substituted phenyl.

Het particularly preferably represents 1,2,4-thiadiazolyl or1,3,4-thiadiazolyl which is substituted by fluorine, chlorine, bromineor by in each case optionally fluorine- and/or chlorine-substitutedmethyl, ethyl or phenyl.

R particularly preferably represents methyl, ethyl, n- or i-propyl, n-,i-, s- or t-butyl, 2-propenyl, 1-methyl-2-propenyl, 2-butenyl,2-propinyl, 1-methyl-2-propinyl, 2-butinyl.

Ar very particularly preferably represents optionally fluorine- orchlorine-substituted phenyl.

Het very particularly preferably represents 1,3,4-thiadiazolyl which issubstituted by chlorine, bromine or by fluorine- and/orchlorine-substituted methyl.

R very particularly preferably represents methyl, ethyl, n- or i-propyl,n-, i-, s- or t-butyl.

Examples of compounds of the formula (I) to be used as mixing partnersaccording to the invention are:

-   N-i-propyl-N-phenyl-α-(5-trifluoromethyl-1,3,4-thiadiazol-2-yl-oxy)-acetamide,    N-i-propyl-N-(2-chloro-phenyl)-α-(5-trifluoromethyl-1,3,4-thiadiazol-2-yl-oxy)-acetamide,    N-i-propyl-N-(3-chloro-phenyl)-α-(5-trifluoromethyl-1,3,4-thiadiazol-2-yl-oxy)-acetamide,    N-i-propyl-N-(4-chloro-phenyl)-α-(5-trifluoromethyl-1,3,4-thiadiazol-2-yl-oxy)-acetamide,    N-i-propyl-N-(2-fluoro-phenyl)-α-(5-trifluoromethyl-1,3,4-thiadiazol-2-yl-oxy)-acetamide,    N-i-propyl-N-(3-fluoro-phenyl)-α-(5-trifluoromethyl-1,3,4-thiadiazol-2-yl-oxy)-acetamide,    N-1-propyl-N-(4-fluoro-phenyl)-α-(5-trifluoro-methyl-1,3,4-thiadiazol-2-yl-oxy)-acetamide.

A mixing component of the formula (I) which may be particularlyemphasized is the compoundN-i-propyl-N-(4-fluoro-phenyl)-α-(5-trifluoromethyl-1,3,4-thiadiazol-2-yl-oxy)-acetamide(flufenacet)—hereinbelow referred to as compound (1-1).

The compounds of the formula (I) are described in the patentapplications or patents mentioned above.

According to their chemical structure, the active compounds of group 2can be assigned to the following classes of active compounds:

-   -   amides (for example beflubutamid), arylheterocycles (for example        azafenidin, benzfendizone, butafenacil-allyl, cinidon-ethyl,        fluazolate, flumioxazin, oxaziclomefone, profluazol,        pyraflufen-ethyl, pyridatol), aryloxyphenoxypropionates (for        example fen-oxaprop-P-ethyl, fluazifop-P-butyl,        haloxyfop-P-methyl, quizalofop-P-ethyl), carboxylic acid        derivatives (for example quinclorac, triclopyr),        chloroacetamides (for example dimethenamid-P, propisochlor),        cyclohexanediones (for example butroxydim, clefoxydim,        cycloxydim), dinitroanilines (for example benfluralin,        oryzalin), imidazolinones (for example imazamox), isoxazoles        (for example isoxachlortole), pyridines (for example thiazopyr),        pyrimidinyl(thio)benzoates (for example pyribenzoxim,        pyriftalid, pyriminobac-methyl, pyrithiobac-sodium),        sulphonylureas (for example azimsulfuron,        flupyrsulfuron-methyl-sodium, foramsulfuron,        iodosulfuron-methyl-sodium, mesosulfuron, trifloxysulfuron,        triflusulfuron-methyl), tetrazolinones (for example        fentrazamide), triazoles (for example amitrole), triazolinones        (for example flucarbazone-sodium, procarbazone-sodium),        triazolopyrimidines (for example cloransulam-methyl, diclosulam,        florasulam), triketones (for example mesotrione).

From among the active compounds of group 2, particular emphasis is givento the following mixing components:

-   -   azimsulfuron, beflubutamid, butafenacil-allyl, cinidon-ethyl,        cloransulam-methyl, clefoxydim, diclosulam, fenoxaprop-P-ethyl,        florasulam, flupyrsulfuron-methyl-sodium, foramsulfuron,        imazamox, iodosulfuron-methyl-sodium, isoxachlortole,        mesosulfuron, oxaziclomefone, procarbazone-sodium, pyriftalid,        pyrithiobac-sodium, quinclorac, trifloxysulfuron.

From this group, beflubutamid is a very particularly interesting mixingcomponent.

From this group, butafenacil-allyl is a further very particularlyinteresting mixing component.

From this group, cinidon-ethyl is a further very particularlyinteresting mixing component.

From this group, clefoxydim is a further very particularly interestingmixing component.

From this group, cloransulam-methyl is a further very particularlyinteresting mixing component.

From this group, diclosulam is a further very particularly interestingmixing component.

From this group, florasulam is a further very particularly interestingmixing component.

From this group, flupyrsulfuron-methyl-sodium is a further veryparticularly interesting mixing component.

From this group, foramsulfuron is a further very particularlyinteresting mixing component.

From this group, imazamox is a further very particularly interestingmixing component.

From this group, iodosulfuron-methyl-sodium is a further veryparticularly interesting mixing component.

From this group, isoxachlortole is a further very particularlyinteresting mixing component.

From this group, mesosulfuron is a further very particularly interestingmixing component.

From this group, oxaziclomefone is a further very particularlyinteresting mixing component.

From this group, procarbazone-sodium is a further very particularlyinteresting mixing component.

From this group, trifloxysulfuron is a further very particularlyinteresting mixing component.

The compositions according to the invention preferably comprise one ortwo active compounds of group 1, one to three active compounds of group2 and optionally one active compound of group 3.

In particular, the compositions according to the invention comprise oneactive compound of group 1, one or two active compounds of group 2 andoptionally one active compound of group 3.

Surprisingly, it has now been found that the above-defined activecompound combinations of the heteroaryloxy-acetamides of the formula (I)and the above-mentioned active compounds of group 2 exhibit aparticularly high herbicidal activity combined with very good crop plantcompatibility and can be used for the selective control ofmonocotyledonous and dicotyledonous weeds in a variety of crops, inparticular in barley, potatoes, maize, rice, soya beans and wheat, andadditionally also for controlling monocotyledonous and dicotyledonousweeds in the semi- and non-selective field.

Surprisingly, the herbicidal activity of the active compoundcombinations according to the invention, of compounds of theabovementioned groups 1 and 2 exceeds the total of the actions of theindividual active compounds considerably.

Thus, not just a complementation of actions but a synergistic effect ispresent which could not have been predicted. The novel active compoundcombinations are well tolerated in a variety of crops, also effectinggood control of weeds which are otherwise difficult to control. Thus,the novel active compound combinations are a valuable addition to theherbicides.

The synergistic effect of the active compound combinations according tothe invention is particularly strongly pronounced in certainconcentration ratios. However, the weight ratios of the active compoundsin the active compound combinations may be varied within relatively wideranges. In general, from 0.01 to 1000 parts by weight, preferably from0.02 to 500 parts by weight and particularly preferably from 0.05 to 100parts by weight of active compound(s) of group 2 are used per part byweight of active compound of the formula (I).

The following may be particularly emphasized as mixing components fromamongst the active compounds of group 3:

-   1-methyl-hexyl 5-chloro-quinoline-8-oxy-acetate    (cloquintocet-mexyl), ethyl    4,5-dihydro-5,5-diphenyl-3-isoxazolecarboxylate (isoxadifen-ethyl)    and    diethyl-1-(2,4-di-chloro-phenyl)-4,5-dihydro-5-methyl-1H-pyrazole-3,5-dicarboxylate    (mefenpyr-diethyl) to improve tolerance in cereals, and    4-dichloroacetyl-1-oxa-4-aza-spiro[4.5]-decane (AD-67),    1-dichloroacetyl-hexahydro-3,3,8a-trimethylpyrrolo[1,2-a]-pyrimidin-6(2H)-one    (BAS-145138),    4-dichloroacetyl-3,4-dihydro-3-methyl-2H-1,4-benzoxazine    (benoxacor), 2,2-dichloro-N,N-di-2-propenyl-acetamide (dichlormid),    2,2-dichloro-N-(2-oxo-2-(2-propenylamino)-ethyl)-N-(2-propenyl)-acetamide    (DKA-24), 3-dichloroacetyl-5-(2-furanyl)-2,2-dimethyl-oxazolidine    (furilazole, MON-13900),    3-dichloroacetyl-2,2,5-trimethyl-oxazolidine (R-29148) to improve    tolerance in maize.

Examples of active compound combinations according to theinvention—optionally also including safeners—which may be mentioned are:

-   -   flufenacet+azimsulfuron, flufenacet+beflubutamid,        flufenacet+beflubutamid+mefenpyr-diethyl,        flufenacet+beflubutamid+cloquintocet-mexyl,        flufenacet+butafenacil-allyl, flufenacet+cinidon-ethyl,        flufenacet+clefoxydim, flufenacet+diclosulam,        flufenacet+fenoxaprop-P-ethyl+mefenpyr-diethyl,        flufenacet+florasulam, flufenacet+florasulam+mefenpyr-diethyl,        flufenacet+florasulam+cloquintocet-mexyl,        flufenacet+flupyrsulfuron-methyl-sodium,        flufenacet+flupyrsulfuron-methyl-sodium+mefenpyr-diethyl,        flufenacet+flupyrsulfuron-methyl-sodium+cloquintocet-mexyl,        flufenacet+foramsulfuron,        flufenacet+foramsulfuron+mefenpyr-diethyl,        flufenacet+foramsulfuron+cloquintocet-mexyl,        flufenacet+foramsulfuron+benoxacor,        flufenacet+foramsulfuron+dichlormid,        flufenacet+foramsulfuron+R-29148,        flufenacet+foramsulfuron+AD-67, flufenacet+imazamox,        flufenacet+iodosulfuron-methyl-sodium,        flufenacet+iodosulfuron-methyl-sodium+mefenpyr-diethyl,        flufenacet+iodosulfuron-methyl-sodium+cloquintocet-mexyl,        flufenacet+isoxachlortole, flufenacet+mesosulfuron,        flufenacet+oxaziclomefone, flufenacet+procarbazone-sodium,        flufenacet+procarbazone-sodium+mefenpyr-diethyl,        flufenacet+procarbazone-sodium+cloquintocet-mexyl,        flufenacet+pyriftalid, flufenacet+pyrithiobac-sodium,        flufenacet+quinclorac, flufenacet+trifloxysulfuron.

It must be considered as surprising that, from amongst a large number ofknown safeners or antidotes capable of antagonizing the harmful effectof a herbicide on the crop plants, it is precisely the abovementionedcompounds of group 3 which are capable of almost completely compensatingthe harmful effect, on the crop plants, of active compounds of theformula (I) and their salts, if appropriate also in combination with oneor more of the abovementioned active compounds of group 2, withoutadversely affecting the herbicidal efficacy towards the weeds.

Even without addition of an active compound of group 2, the followingactive compounds of group 3 have been found to be highly suitableaccording to the invention for improving the crop plant compatibility ofthe active compounds of the formula (I):

-   1-dichloroacetyl-hexahydro-3,3,8a-trimethylpyrrolo[1,2-a]-pyrimidin-6(2H)-one    (dicyclonon, BAS-145138), ethyl    4,5-dihydro-5,5-diphenyl-3-isoxazolcarboxylate (isoxadifen-ethyl),    diethyl    1-(2,4-dichlorophenyl)-4,5-dihydro-5-methyl-1H-pyrazole-3,5-dicarboxylate    (mefenpyr-diethyl), 3-dichloroacetyl-2,2-dimethyl-oxazolidine    (R-28725), 3-dichloroacetyl-2,2,5-trimethyl-oxazolidine (R-29148)    and methyl 1-(2-chloro-phenyl)-5-phenyl-1H-pyrazole-3-carboxylate.

The advantageous effect of the crop plant compatibility of the activecompound combinations according to the invention is likewiseparticularly strongly pronounced at certain concentration ratios.However, the weight ratios of the active compounds in the activecombinations can be varied within relatively wide ranges. In general,from 0.001 to 1000 parts by weight, preferably from 0.01 to 100 parts byweight and particularly preferably from 0.1 to 10 parts by weight ofactive compound(s) of group 3 are used per part by weight of activecompound of the formula (I).

All plants and plant parts can be treated in accordance with theinvention. Plants are to be understood as meaning in the present contextall plants and plant populations such as desired and undesired wildplants or crop plants (inclusive of naturally occurring crop plants).Crop plants can be plants which can be obtained by conventional plantbreeding and optimization methods or by biotechnological and recombinantmethods or by combinations of these methods, inclusive of the transgenicplants and inclusive of the plant varieties protectable or notprotectable by plant breeders' rights. Plant parts are to be understoodas meaning all aerial and subterranean plant parts and organs of theplants such as shoot, leaf, flower and root, examples which may bementioned being leaves, needles, stalks, trunks, flowers, fruitingbodies, fruits, seeds, roots, tubers and rhizomes. The plant parts alsoinclude vegetative and generative propagation material, for examplecuttings, tubers, rhizomes, seedlings and seeds.

The treatment according to the invention, of the plant and plant partswith the active compounds is carried out directly or by allowing thecompounds to act on the surroundings, environment or storage space bythe customary treatment methods, for example by immersion, spraying,evaporation, fogging, scattering, painting on and, in the case ofpropagation material, in particular in the case of seeds, also byapplying one or more coats.

Amongst the plants obtained by biotechnological and recombinant methods,or by combining these methods, plants which are emphasized are thosewhich tolerate so-called ALS, 4-HPPD, EPSP and/or PPO inhibitors, suchas, for example, Acuron plants.

The active compounds according to the invention can be used, forexample, in the following plants:

-   -   dicotyledonous weeds of the genera: Abutilon, Amaranthus,        Ambrosia, Anoda, Anthemis, Aphanes, Atriplex, Bellis, Bidens,        Capsella, Carduus, Cassia, Centaurea, Chenopodium, Cirsium,        Convolvulus, Datura, Desmodium, Emex, Erysimum, Euphorbia,        Galeopsis, Galinsoga, Galium, Hibiscus, Ipomoea, Kochia, Lamium,        Lepidium, Lindernia, Matricaria, Mentha, Mercurialis, Mullugo,        Myosotis, Papaver, Pharbitis, Plantago, Polygonum, Portulaca,        Ranunculus, Raphanus, Rorippa, Rotala, Rumex, Salsola, Senecio,        Sesbania, Sida, Sinapis, Solanum, Sonchus, Sphenoclea,        Stellaria, Taraxacum, Thlaspi, Trifolium, Urtica, Veronica,        Viola, Xanthium;    -   dicotyledonous crops of the genera: Arachis, Beta, Brassica,        Cucumis, Cucurbita, Helianthus, Daucus, Glycine, Gossypium,        Ipomoea, Lactuca, Linum, Lycopersicon, Nicotiana, Phaseolus,        Pisum, Solanum, Vicia;    -   monocotyledonous weeds of the genera: Aegilops, Agropyron,        Agrostis, Alopecurus, Apera, Avena, Brachiaria, Bromus,        Cenchrus, Commelina, Cynodon, Cyperus, Dactyloctenium,        Digitaria, Echinochloa, Eleocharis, Eleusine, Eragrostis,        Eriochloa, Festuca, Fimbristylis, Heteranthera, Imperata,        Ischaemum, Leptochloa, Lolium, Monochoria, Panicum, Paspalum,        Phalaris, Phleum, Poa, Rottboellia, Sagittaria, Scirpus,        Setaria, Sorghum;    -   monocotyledonous crops of the genera: Allium, Ananas, Asparagus,        Avena, Hordeum, Oryza, Panicum, Saccharum, Secale, Sorghum,        Triticale, Triticum, Zea.

However, the use of the active compound combinations according to theinvention is in no way restricted to these genera, but also extends inthe same manner to other plants.

The active compound combinations to be used in accordance with theinvention can be employed not only in conventional cultivation methods(suitably spaced row crops), in plantation crops (for examplegrapevines, fruit, citrus) and in industrial plants and railtracks, onpaths and squares, but also for stubble treatment and in the minimumtillage method. They are furthermore suitable as dessicants (haulmkilling in, for example, potatoes) or as defoliants (for example incotton). They are furthermore suitable for use on non-crop areas. Otherfields of application are nurseries, forests, grassland and theproduction of ornamentals.

The active compound combinations can be converted into the customaryformulations such as solutions, emulsions, wettable powders,suspensions, powders, dusts, pastes, soluble powders, granules,suspo-emulsion concentrates, natural and synthetic materials impregnatedwith active compound, and microencapsulations in polymeric materials.

These formulations are produced in a known manner, for example by mixingthe active compounds with extenders, that is, liquid solvents and/orsolid carriers, optionally with the use of surfactants, that is,emulsifiers and/or dispersants and/or foam formers.

If the extender used is water, it is also possible to employ, forexample, organic solvents as cosolvents. The following are essentiallysuitable as liquid solvents: aromatics such as xylene, toluene, oralkylnaphthalenes, chlorinated aromatics and chlorinated aliphatichydrocarbons such as chlorobenzenes, chloroethylenes or methylenechloride, aliphatic hydrocarbons such as cyclohexane or paraffins, forexample mineral oil fractions, mineral and vegetable oils, alcohols suchas butanol or glycol and their ethers and esters, ketones such asacetone, methyl ethyl ketone, methyl isobutyl ketone or cyclohexanone,strongly polar solvents such as dimethylformamide and dimethylsulphoxide, or else water.

Solid carriers which are suitable are for example ammonium salts andground natural minerals such as kaolins, clays, talc, chalk, quartz,attapulgite, montmorillonite or diatomaceous earth, and ground syntheticmaterials such as highly-dispersed silica, alumina and silicates;suitable solid carriers for granules are for example crushed andfractionated natural rocks such as calcite, marble, pumice, sepioliteand dolomite, or else synthetic granules of inorganic and organic meals,and granules of organic material such as sawdust, coconut shells, maizecobs and tobacco stalks; suitable emulsifiers and/or foam formers arefor example nonionic and anionic emulsifiers such as polyoxyethylenefatty acid esters, polyoxyethylene fatty alcohol ethers, for examplealkylaryl polyglycol ethers, alkylsulphonates, alkyl sulphates,arylsulphonates, or else protein hydrolysates; suitable dispersants arefor example ligninosulphite waste liquors and methylcellulose.

Tackifiers such as carboxymethylcellulose and natural and syntheticpolymers in the form of powders, granules or latices, such as gumarabic, polyvinyl alcohol and polyvinyl acetate, or else naturalphospholipids such as cephalins and lecithins and syntheticphospholipids can be used in the formulations. Other possible additivesare mineral and vegetable oils.

It is possible to use colorants such as inorganic pigments, for exampleiron oxide, titanium oxide and Prussian Blue, and organic dyestuffs,such as alizarin dyestuffs, azo dyestuffs and metal phthalocyaninedyestuffs, and trace nutrients such as salts of iron, manganese, boron,copper, cobalt, molybdenum and zinc.

The formulations generally comprise between 0.1 and 95 percent by weightof active compounds, preferably between 0.5 and 90%.

The active compound combinations according to the invention aregenerally applied in the form of ready mixes. However, the activecompounds contained in the active compound combinations may also beapplied in the form of individual formulations which are mixed upon use,that is, in the form of tank mixes.

The novel active compound combinations, as such or in theirformulations, may furthermore also be used as a mixture with other knownherbicides, again with ready mixes or tank mixes being possible. Amixture with other known active compounds such as fungicides,insecticides, acaricides, nematicides, bird repellents, growthsubstances, plant nutrients and soil conditioners is also possible. Itmay furthermore be advantageous for specific applications, in particularfor the post-emergence method, to incorporate into the formulationsplant-compatible mineral or vegetable oils (for example the commercialproduct “Oleo Dupont 11E”) or ammonium salts such as, for example,ammonium sulphate or ammonium thiocyanate, as further additives.

The novel active compound combinations can be used as such, in the formof their formulations or the use forms which can be prepared from theseformulations by further dilution, such as ready-to-use solutions,suspensions, emulsions, powders, pastes and granules. Application iseffected in the customary manner, for example by pouring, spraying,atomizing, dusting or broadcasting.

The active compound combinations according to the invention can beapplied before and after emergence of the plants, that is to say by thepre- and post-emergence method. They may also be incorporated into thesoil prior to sowing.

A synergistic effect in herbicides is always present when the herbicidalaction of the active compound combination exceeds the action of theactive compounds when applied individually.

The expected action for a given combination of two herbicides can becalculated as follows (cf. COLBY, S. R.: “Calculating synergistic andantagonistic responses of herbicide combinations”, Weeds 15, pages20-22, 1967):

If

-   X=% damage by herbicide A (active compound of the formula I) at an    application rate of p kg/ha    and-   Y=% damage by herbicide B (active compound of the formula II) at an    application rate of q kg/ha    and-   E=the expected damage of herbicides A+B at an application rate of    p+q kg/ha,    then-   E=x+Y—(X*Y/100).

If the actual damage exceeds the calculated value, the combination has asuperadditive effect, that is to say a synergistic effect.

The active compound combinations of the present invention do indeed havethe property that their actual herbicidal activity is stronger than thecalculated activity, i.e. the novel active compound combinations actsynergistically.

1-10. (canceled)
 11. A composition comprising an herbicidally effectiveamount of an active compound combination consisting of (a) aheteroaryloxy-acetamide of the formula (I)

in which Ar represents optionally halogen-, C₁-C₄-alkyl-, orC₁-C₄-halogenoalkyl-substituted phenyl, Het represents thiadiazolyl thatis substituted by halogen or by optionally halogen-substitutedC₁-C₄-alkyl or phenyl, and R represents alkyl, alkenyl, or alkynylhaving in each case up to 4 carbon atoms, (b) one or more herbicidallyactive compounds, other than the heteroaryloxy-acetamide of the formula(I), selected from the group consisting of 1H-1,2,4-triazol-3-amine(amitrole),2-[2,4-dichloro-5-(2-propynyloxy)-phenyl]-5,6,7,8-tetrahydro-1,2,4-triazolo[4,3-a]pyridin-3(2H)-one(azafenidin),N-(4,6-dimethoxy-pyrimidin-2-yl)-N′-[1-methyl-4-(2-methyl-2H-tetrazol-5-yl)-1H-pyrazol-5-ylsulphonyl]urea(azimsulfuron),N-benzyl-2-(4-fluoro-3-trifluoromethyl-phenoxy)butanamide(beflubutamid),N-butyl-N-ethyl-2,6-dinitro-4-trifluoro-methyl-benzeneamine(benfluralin), methyl2-[2-[4-(3,6-dihydro-3-methyl-2,6-dioxo-4-trifluoromethyl-1(2H)-pyrimidinylphenoxymethyl]-5-ethyl-phenoxy-propanoate(benzfendizone),3-(2-chloro-4-methylsulphonyl-benzoyl)-4-phenylthio-bicyclo[3.2.1]oct-3-en-2-one(benzobicyclon),2-(1-ethoximino-propyl)-3-hydroxy-5-[2,4,6-trimethyl-3-(1-oxo-butyl)phenyl]-2-cyclohexen-1-one(butroxydim),2-[1-[(3-chloro-2-propenyl)-oxy-imino]propyl]-3-hydroxy-5-(tetrahydro-2H-pyran-4-yl)-2-cyclohexen-1-one(caloxydim, tepraloxydim),2-[1-[2-(4-chloro-phenoxy)]propoxyaminobutyl]-5-(tetrahydro-2H-thiopyran-3-yl)-1,3-cyclohexanedione(clefoxydim),(E,E)-(+)-2-[1-[[(3-chloro-2-propenyl)-oxy]imino]propyl]-3-hydroxy-2-cyclohexen-1-one(clethodim), methyl3-chloro-2-[[(5-ethoxy-7-fluoro[1,2,4]triazolo[1,5-c]pyrimidin-2-yl)sulphonyl]amino]-benzoate(cloransulam-methyl),2-(1-ethoximinobutyl)-3-hydroxy-5-(tetrahydro-2H-thiopyran-3-yl)-2-cyclohexen-1-one(cycloxydim),N-(2,6-dichloro-phenyl)-5-ethoxy-7-fluoro[1,2,4]triazolo[1,5-c]pyrimidine-2-sulphonamide(diclosulam),2-[1-[(3,5-difluorophenyl)aminocarbonyl-hydrazono]ethyl]-pyridine-3-carboxylicacid (diflufenzopyr),2-[2-(3-chlorophenyl)oxiranyl-methyl]-2-ethyl-1H-indene-1,3(2H)-dione(epropodan),ethyl[2-chloro-4-fluoro-5-(5-methyl-6-oxo-4-trifluoromethyl-1(6H)-pyridazinyl)phenoxy]acetate (flufenpyr),2-[[[[(4,6-dimethoxy-2-pyrimidinyl)amino]carbonyl]amino]-sulphonyl]-4-formylamino-N,N-dimethyl-benzamide(foramsulfuron),2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl)-5-(methoxy-methyl)-3-pyridinecarboxylicacid (imazamox),(4-chloro-2-methylsulphonyl-phenyl)(5-cyclopropyl-isoxazol-4-yl)methanone(isoxachlortole), methyl2-[[[[(4,6-dimethoxy-2-pyrimidinyl)amino]carbonyl]amino]sulphonyl]-4-[[(methylsulphonyl)amino]methyl]benzoate(mesosulfuron),3-[1-(3,5-dichlorophenyl)-1-i-propyl]-2,3-dihydro-6-methyl-5-phenyl-4H-1,3-oxazin-4-one(oxaziclomefone),2-(2,2-difluoroethoxy)-N-(5,8-dimethoxy[1,2,4]triazolo-[1,5-c]pyrimidin-2-yl)-6-trifluoromethylbenzenesulphonamide(penoxsulam),2-chloro-N-(2-ethoxyethyl)-N-(2-methyl-1-phenyl-1-propenyl)acetamide(pethoxamid),1-chloro-N-[2-chloro-4-fluoro-5-[(6S,7aR)-6-fluoro-tetrahydro-1,3-dioxo-1H-pyrrolo[1,2-c]imidazol-2(3H)-yl]phenyl]methanesulphonamide(profluazol),(R)-[2-[[(1-methyl-ethylidene)amino]oxy]ethyl]2-[4-(6-chloro-2-quinoxalinyloxy)phenoxy]propanoate(propaquizafop),2-chloro-N-(2-ethyl-6-methyl-phenyl)-N-[(1-methylethoxy)methyl]acetamide(propisochlor),1-(3-chloro-4,5,6,7-tetrahydropyrazolo[1,5-a]pyridin-2-yl)-5-(methyl-2-propynyl-amino)-1H-pyrazol-4-carbonitrile(pyraclonil),ethyl[2-chloro-5-(4-chloro-5-difluoromethoxy-1-methyl-1H-pyrazol-3-yl)-4-fluorophenoxy]acetate(pyraflufen-ethyl), 6-chloro-3-phenyl-pyridazin-4-ol (pyridatol),7-[(4,6-dimethoxy-2-pyrimidinyl)thio]-3-methyl-[(3H)-isobenzofuranone(pyriftalide), methyl 2-(4,6-dimethoxy-pyrimidin-2-yl-oxy)benzoate(pyriminobac-methyl), the sodium salt of2-chloro-6-(4,6-dimethoxypyrimidin-2-ylthio)benzoate(pyrithiobac-sodium), methyl2-difluoromethyl-5-(4,5-dihydrothiazol-2-yl)-4-(2-methylpropyl)-6-trifluoromethyl-pyridine-3-carboxylate(thiazopyr), (3,5,6-trichloro)pyridin-2-yl-oxyacetic acid (triclopyr),the sodium salt ofN-[[(4,6-dimethoxy-2-pyrimidinyl)amino]carbonyl]-3-(2,2,2-trifluoroethoxy)-2-pyridinesulphonamide(trifloxysulfuron),N-[4-dimethylamino-6-(2,2,2-trifluoroethoxy)-1,3,5-triazin-2-yl]-N′-(2-methoxycarbonylphenylsulphonyl)urea(triflusulfuron-methyl), andN-[[(4,6-dimethoxy-2-pyrimidinyl)amino]carbonyl]-3-(N-methyl-N-methylsulphonyl-amino])-2-pyridinesulphonamide,and (c) optionally, a compound that improves crop plant toleranceselected from the group consisting of4-dichloroacetyl-1-oxa-4-aza-spiro[4.5]decane (AD-67),1-dichloroacetyl-hexahydro-3,3,8a-trimethylpyrrolo[1,2-a]pyrimidin-6(2H)-one(dicyclonon, BAS-145138),4-dichloroacetyl-3,4-dihydro-3-methyl-2H-1,4-benzoxazine (benoxacor),1-methyl hexyl 5-chloroquinoline-8-oxyacetate (cloquintocet-mexyl),α-(cyanomethoximino)phenylacetonitrile (cyometrinil),2,2-dichloro-N-(2-oxo-2-(2-propenylamino)ethyl)-N-(2-propenyl)acetamide(DKA-24), 2,2-dichloro-N,N-di-2-propenylacetamide (dichlormid),N-(4-methylphenyl)-N′-(1-methyl-1-phenylethyl)urea (dymron),4,6-dichloro-2-phenylpyrimidine (fenclorim), ethyl1-(2,4-dichlorophenyl)-5-trichloromethyl-1H-1,2,4-triazole-3-carboxylate(fenchlorazol-ethyl), phenylmethyl2-chloro-4-trifluoromethyl-thiazole-5-carboxylate (flurazole),4-chloro-N-(1,3-dioxolan-2-yl-methoxy)-α-trifluoroacetophenone oxime(fluxofenim), 3-dichloroacetyl-5-(2-furanyl)-2,2-dimethyloxazolidine(furilazole, MON-13900), ethyl4,5-dihydro-5,5-diphenyl-3-isoxazolecarboxylate (isoxadifen-ethyl),diethyl-1-(2,4-dichloro-phenyl)-4,5-dihydro-5-methyl-1H-pyrazole-3,5-dicarboxylate(mefenpyr-diethyl), 2-dichloromethyl-2-methyl-1,3-dioxolane (MG-191),1,8-naphthalene-dicarboxylic anhydride,α-(1,3-dioxolan-2-yl-methoximino)phenylacetonitrile (oxabetrinil),2,2-dichloro-N-(1,3-dioxolan-2-yl-methyl)-N-(2-propenyl)acetamide(PPG-1292), 3-dichloroacetyl-2,2-dimethyl-oxazolidine (R-28725),3-dichloroacetyl-2,2,5-trimethyl-oxazolidine (R-29148), methyl1-(2-chloro-phenyl)-5-phenyl-1H-pyrazole-3-carboxylate, andN-(2-methoxybenzoyl)-4-[(methylaminocarbonyl)amino]benzenesulphonamide.12. A composition according to claim 11 wherein, in the formula (I), Arrepresents optionally fluorine-, chlorine-, bromine-, methyl-, ethyl-,or trifluoromethyl-substituted phenyl, Het represents 1,2,4-thiadiazolylor 1,3,4-thiadiazolyl substituted by fluorine, chlorine, bromine or byin each case optionally fluorine- and/or chlorine-substituted methyl,ethyl, n- or i-propyl, or phenyl, and R represents methyl, ethyl, n- ori-propyl, n-, i-, s-, or t-butyl, 2-propenyl, 1-methyl-2-propenyl,2-butenyl, 2-propynyl, 1-methyl-2-propynyl, or 2-butynyl.
 13. Acomposition according to claim 11 wherein the heteroaryloxy-acetamide offormula (I) isN-i-propyl-N-(4-fluoro-phenyl)-α-(5-trifluoromethyl-1,3,4-thiadiazol-2-yl-oxy)acetamide.14. A composition according to claim 11 wherein the herbicidally activecompounds of component (b) are selected from the group consisting ofazimsulfuron, beflubutamid, clefoxydim, cloransulam-methyl, diclosulam,foramsulfuron, imazamox, isoxachlortole, mesosulfuron, oxaziclomefone,pyriftalid, pyrithiobac-sodium, and trifloxysulfuron.
 15. A compositionaccording to claim 11 wherein the heteroaryloxy-acetamide of formula (I)isN-i-propyl-N-(4-fluoro-phenyl)-α-(5-trifluoromethyl-1,3,4-thiadiazol-2-yl-oxy)acetamideand the herbicidally active compound of component (b) is mesosulfuron.16. A composition according to claim 11 wherein the compounds ofcomponent (c) that improve crop plant tolerance are selected from groupconsisting of 1-methyl-hexyl 5-chloroquinoline-8-oxyacetate(cloquintocet-mexyl), ethyl4,5-dihydro-5,5-diphenyl-3-isoxazolecarboxylate (isoxadifen-ethyl),diethyl-1-(2,4-dichlorophenyl)-4,5-dihydro-5-methyl-1H-pyrazole-3,5-dicarboxylate(mefenpyr-diethyl), 4-dichloroacetyl-1-oxa-4-aza-spiro[4.5]decane(AD-67),1-dichloroacetyl-hexahydro-3,3,8a-trimethylpyrrolo[1,2-a]pyrimidin-6(2H)-one(BAS-145138), 4-dichloroacetyl-3,4-dihydro-3-methyl-2H-1,4-benzoxazine(benoxacor), 2,2-dichloro-N,N-di-2-propenylacetamide (dichlormid),2,2-dichloro-N-(2-oxo-2-(2-propenyl-amino)ethyl)-N-(2-propenyl)acetamide(DKA-24), 3-dichloroacetyl-5-(2-furanyl)-2,2-dimethyloxazolidine(furilazole, MON-13900), and3-dichloroacetyl-2,2,5-trimethyl-oxazolidine (R-29148).
 17. Acomposition according to claim 11 wherein from 0.01 to 1000 parts byweight of the herbicidally active compounds of component (b) are usedper part by weight of the heteroaryloxy-acetamide of formula (I).
 18. Acomposition according to claim 11 wherein from 0.001 to 1000 parts byweight of one or more compounds of component (c) that improve crop planttolerance are used per part by weight of the heteroaryloxy-acetamide offormula (I) or a mixture thereof with an herbicidally active compound ofcomponent (b).
 19. A method for controlling undesirable plantscomprising allowing a composition according to claim 11 to act on theundesirable plants and/or their habitat.
 20. A process for preparing anherbicidal composition comprising mixing a composition according toclaim 11 with surfactants and/or extenders.